


Urine Luck

by snasational



Category: Undertale (Video Game)
Genre: Cherryberry - Freeform, M/M, Omorashi, Underfell Sans (Undertale), Underswap Sans (Undertale)
Language: English
Status: Completed
Published: 2021-02-22
Updated: 2021-02-22
Packaged: 2021-03-12 13:26:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,677
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29635308
Author URL: https://archiveofourown.org/users/snasational/pseuds/snasational
Summary: “It’s not that!” Blue snaps defensively.“Then what is it?”“I really have to pee.” He finally blurts out.
Relationships: Sans/Sans (Undertale)
Comments: 5
Kudos: 68





	Urine Luck

**Author's Note:**

> Okay I have a piss kink so what 
> 
> I was going to write some piss stuff with Cross, but this came out instead. I dedicate this to tinystarfruits uwu

“You know, you’re kind of a liar.” 

Blue looks up from his comic with a frown. Red is sitting next to him, slouched on the couch with his head in one hand and the remote in his other. Sans’ underground doesn’t have much T.V, so the skeleton has settled on mindlessly flipping through channels out of boredom. Blue doesn’t blame him; Naptstaton is  _ way  _ better than Mettaton. The awful television is definitely the worst part of being stuck here. 

Papyrus had very choice words for him when he voiced his opinion. Blue thinks he’s blinded by Mettaton’s horribly bright teeth. 

“It is very rude to throw out accusations like that, Red.” Blue scolds, tone displeased. “I have never lied to you before.”   
  


“Not out right.” He hums. His singular glowing eye pulses lazily. Blue can’t fathom why Red keeps his magic activated all of the time. It seems like a waste of magic and when pressed on the issue Red never gives a solid answer. “But you’re an awfully good actor, ain’t you?” 

His frown deepens. “What’s that supposed to mean?” 

Red shrugs. “You pretend to be something you ain’t. Got the whole world fooled into thinking you’re some energetic, happy go lucky dumbass. But you’re  _ not.  _ And to be honest, I kinda respect that. It’s a good front.” 

Red stops on another MTT Brand show. A cooking network that’s loud and annoying. The segment features more chainsaws than normal, something that definitely draws the bigger skeleton in. It’s strange how Red loves watching violent things but doesn’t like participating in them. 

Blue has tried to get Red to fight him, but both he and Sans would rather watch from the sidelines as he takes on Papyrus or Edge. A shame. Red would be a good fighter, he knows he has to be. The edgey set of brothers never talk about it and yet it’s obvious that the world they come from is extremely hostile.

“I disagree entirely.” Blue huffs. Despite this, he feels like a child that just got caught with their hand in a cookie jar. “My personality is not an act. The Magnificent Sans is naturally flamboyant. Just because you and lazy me are downers doesn’t mean I have to be one too.” 

Red snorts. “Sure, if that helps you sleep better at night.” 

“I don’t need help sleeping at night. I sleep perfectly fine by myself.” He sets down his comic and crosses his arms defensively.

Okay, so maybe he’s a little bit of a pretender. Still, Red shouldn’t go around saying these kinds of things out loud. What if Papy overhears? Blue would hate for his little brother’s perception of him to be ruined. He’s worked hard his entire life to keep him happy by being happy himself. If he sets a good example, Papy will follow it with relative success. But if he sets a bad one? It’ll be a downhill slope for the both of them. 

“It’s just a saying, angelcakes.” 

Even though his tone is nonchalant, there’s a knowing glint in Red’s eye that makes Blue feel weirdly seen. Blue loves being looked at; he doesn’t love being looked  _ through.  _ Like a pane of glass, transparent and obvious for the world to see. Any flaw is magnified and his personality is stripped bare. He hates that. 

“It’s a bad one.” He points out. “Why are you so interested in me all of a sudden, anyways? I understand that my magnificence is hard to ignore, but you’ve never really cared before.”

Red tosses the remote on the end table and begins to play with his rings. He twists them around on his phalanges and rubs at some of the expensive looking stones. His jewelry is neat, Blue has never met someone who wears so much of it. And he never wears the same things, bone-patterned necklace aside. Where does he even get all of those rings? Did he bring his entire collection with him when they were pulled into this timeline?

“You’re a Sans. Just thought I’d remind you by pointing out what seems to be a universal Sans trait. You can pretend to be a paps all you want, but at the end of the day we’re still the same person. Reading you like a book is easy peasy lemon squeezy.” 

Blue has never thought of himself as anything but Sans, the idea that he’d be trying to act like Papy is ridiculous. Even when they tacked the name Blue on him, the skeleton still called himself Sans in his head. Responding to a name he didn’t associate with was difficult at first but eventually he got used to it. 

“Am I not up to your ‘Sans’ standards?” 

Red barks out a laugh. Blue is vaguely offended; nothing about this conversation is funny. “Nah. If there was a standard me and the doofus would be  _ way  _ below it. You ain’t a bad person, pumpkin. Just...a little fake, that’s all.” 

“Thanks. The Magnificent Sans appreciates your kind words so much.” Blue says dryly. “You are truly the charmer out of the three of us Sanses, no doubt about it. I am vastly blown away by your flattery.” 

“Good to know that you’d fuck me.” Red winks at him. “The feeling is definitely mutual.”

He stutters and chokes. Blue can feel his face heating up at a rapid rate. While he normally appreciates straightforwardness, he isn’t used to crude confessions. Does this stupid joke even count as confession? Or is he being serious? Blue doesn’t know how to react to this, he’s never been in a relationship before and he has no idea how to navigate this kind of a social interaction. 

“Oh man. Loosen up, yeah? It was a joke.” Red laughs again, the cadence of it deep and smooth. The sound of it only serves to fluster him more. 

“You should not joke about things like that.” Blue stutters out. “It is...it is misleading! And incredibly rude!” 

Red tugs his middle finger ring up and down his digit in a lazy, repetitive motion. It's a pretty ring, although it doesn’t fit his aesthetic much. A silver band as opposed to gold, and on top is a cyan colored crystal. Blue watches as he tugs at it with a rapidly deepening blush. 

Now that the idea of fucking Red has entered his head he can’t seem to shake it. He imagines those thick phalanges shoved up his pussy, pumping in and out lazily as Blue squirms and begs him to go faster. Even better, another vision of Red seated on his cock and riding him fast and hard nearly makes him fall over. 

“So sorry.” Red apologizes without sincerity. 

Edge storms into the house before Blue can respond, swearing and stomping his feet along the way. They both freeze and watch as Papyrus chases after him with placating words. The scene isn’t unusual; Edge tends to get offended and angry rather quickly. And Papyrus is a people pleaser, so of course he won’t let it go unbothered. Blue can relate to that immensely. 

“Heh. They’re so funny.” Sans says from the other side of the couch. He definitely wasn’t there a few seconds ago. “I wonder what happened this time.” 

Sans smells like grease and ketchup. Undoubtedly he was at Grillby’s again. 

“Who the fuck knows. I should go see what’s up though.” In a blink, Red is gone too and he’s left alone with Sans. Those shortcuts are useful, Blue wishes they’d teach it to him. 

“They went to see Undyne.” Sans supplies casually after Red is gone.

The image of Alphys’ dorky girlfriend pops into his head at the mention of her. He likes Undyne, she always feeds him tons of ramen. But if this world is supposed to be switched around, Undyne must be more aggressive. That probably doesn’t clash well with Edge. 

“Oh, I hope they had fun!” He says despite knowing the visit was probably anything but fun. 

“Yeah. Me too.” Sans yawns and stretches his arms before slumping down in a fashion reminiscent of Red. “By the way, your brother is passed out in the snow. I would’ve picked him up but he’s kind of heavy.” 

“Oh stars, not again.” Blue is up and out of the house fast. Getting his brother home safely erases all other thoughts and he forgets about his conversation with Red. 

That is until later, when he’s curled up on the couch and staring at the cieling. Loneliness lingers heavily in his soul, a feeling he’s grown accustomed too. What would it be like to actually be with Red? He falls asleep to similar thoughts, longing and infatuation settling deep within his marrow.

-

Red is drunk and they’re stuck in a closet.

Blue doesn’t remember how they got stuck in here exactly, because the night has been a blur of handling drunken skeletons and being the only sober monster within a five mile radius. Blue shouldn’t have agreed to go to Doggo’s party, especially since he hates drinking. He’s had about six cups of water by now while everyone else has been downing beer after beer. 

“You’re elbowing me.” Blue whines. “Move your arm.” 

Red slurs out something indecipherable. He sighs. Red is in no state to shortcut and Blue doesn’t have the ability to do it, so until someone hears his calls for help over the loud music they’re just going to have to sit tight. Which would be fine if Red had a sense of personal space. 

He turns his head and gets a faceful of fur. “Red!” He complains again. “You are being insufferable! Get off of me!” 

Panic wells up inside of him. Two different types of magic begin to build, arousal and...Blue shudders. Now is the  _ worst  _ time to need to expel excess magic! He squirms violently and Red grunts. 

“Mm.” He slurs. He pulls Blue closer. “Smells good. Meant what I said ‘bout you fucking me.” 

“Please get off of me.” He whimpers. The way Red breathes against his skull tickles him, which in turn makes his magic give a painful throb. The need to relieve himself is rapidly becoming overwhelming. Weakly, he palms at Red’s chest.

“Can’t.” He murmurs. “So warm. I’d let you fuck me so hard.” 

Against his will, Blue’s lower half begins to materialize. It makes the need to pee ache even worse. Red seems to realize he’s formed his body, because he presses his hips into Blue’s groin and gives a gentle grind. Blue yelps at the sensation and is mortified when a stream of urine squirts out. 

“Red.” The skeleton warns. 

“But I can feel you.” He pants. “Stiff as a damn rock. Big as fuck too. Come on baby, please?” 

“I can’t right now.” The skeleton bites out. He’d one hundred percent love to bang him against the door, but doing so risks making a wet mess that would disgust Red. 

“Why not?” The tremble in his voice makes it sounds like Red is close to sobbing. Blue can relate to that. “Is this more of your pretending bullshit? What’s the point of acting around me if I can see right through you?” 

“It’s not that!” Blue snaps defensively. 

“Then what is it?” 

“I  _ really  _ have to pee.” He finally blurts out. “And if I fuck you, I’ll definitely pee on you and then you’ll hate me forever because I did something so disgusting.” 

A beat of silence and then laughter. “Oh man. Hilarious. That ain’t no problem, sweetheart.” 

“What-“ 

“Let’s fix your problem, yeah? Wouldn’t want you to hold it in for too long.” Red drops to his knees and begins to undo Blue’s zipper. When Blue tries to stop him, Red bats away his hand. 

“Red, what are you doing?” He gasps. “Did you hear me? I’ll pee on you!” 

“It’s okay.” Red mumbles. He’s focused on undoing everything in the dark. “I’m into that.”

Well. That effectively shuts him up. Blue gapes down at the outline of Red’s skull, disbelief coating his features. He remains still in his bemusement, allowing Red to pull his cock free from his pants. It only breaks when Red laps his tongue at Blue’s weeping dick. 

“Red.” He moans. His cock gives a pitiful twitch. Holding his piss is becoming a challenge. “You can’t be serious.”

“But I am.” 

Red closes his mouth around Blue’s tip and gives a hard suck. At the same time, a hand comes up to cup and fondle at his balls. It’s too much too soon; with a sharp cry a spray of urine shoots from his cock and straight in Red’s mouth. 

Blue’s hands fly to grip at Red’s skull while the skeleton happily sucks down all of his piss. He swallows every last drop, sighing with happiness like he’s drinking the best damned thing in the entire world. It can’t taste good, it’s piss! But from the way Red’s acting, it’s like Blue’s pee is a fine wine. 

When the stream finally stops Red pulls away from his cock with a lewd pop. He gives it a few more affectionate licks before using Blue’s shirt as leverage to pull himself back up on his feet. Blue is at a complete loss of words; he has no idea what to say now. 

“Thanks for the drink.” Red giggles. “It was fuckin’ delicious. You want a taste?” 

_ No, absolutely not.  _ Is what should’ve come from his mouth. Instead, he grabs Red by the fur of his coat and crash his teeth against his. Red recuperates immediately, wrapping his arms around Blue’s frame and deepening the kiss. Blue intertwines their tongues, tasting himself on the other. 

He’s surprised to find that he doesn’t hate the taste. It’s salty and bitter, and even though it’s not exactly pleasant it’s still enough to make him incredibly aroused. Blue never thought in a million years that this would be something he’d actually enjoy. He was with the majority previously, believing that piss is better left in the toilet. 

But after this? His mind has definitely been expanded. 

They pull away after a while spent licking desperately into each other’s mouths. He’s hesitant to let him go, but Red can’t hold his breath as long as he can. The gasps of air Red lets out when they part only spurs on his lust. Blue has been fantasizing about fucking Red since that conversation and now that he doesn’t have to pee anymore nothing is stopping him. 

“You’re the fucking best.” Red tells him breathlessly. “And now you definitely have to fuck me.” 

He doesn’t have to tell him twice. “Stars, yes. The Magnificent Sans would love to have you.”

“Fucking  _ finally _ . I’ve been-“ 

The door opens. 

“There you guys are, we couldn’t find you and I heard a noise in...the...oh.” Sans smiles at them with amusement. “I see that you’re busy.” 

Red scowls at the cockblocker, displeasure written clear as day on his face.

“Don’t close the door!” Blue quickly stops him from shutting them in again. “We can’t open it from the inside.” 

Sans is very obviously biting back laughter. “I’ll leave it cracked. You know, give you privacy to stick your dick back in your pants. See y’all at the house.” 

True to his word, he leaves the door cracked and wonders off. The two of them are silent as they process what just happened. The mood isn’t  _ entirely  _ ruined but this certainly dimmed it. 

“What an ass.” Red spits. 

“He saved us from this closest, Red. Who knows how long we would’ve been stuck here if it weren’t for him.” Blue pats Red on the shoulder appealingly. 

“Still an ass.” 

“I suppose. Let’s go to the house, okay? We could...we could, ah, continue where we left off, maybe?” Blue shuffles his feet, suddenly very shy. He hopes Red doesn’t regret anything that just happened. 

When Red gives him the most lecherous grin he’s ever seen, Blue’s worries are put at ease. 

“Yeah, I was feeling thirsty again anyways

**Author's Note:**

> My Twitter is @ snasational


End file.
